Friction type change speed gears



Nov. 28, 1961 Filed Jan. 28, 1959 F. PERRUCA 3,010,330

FRICTION TYPE CHANGE SPEED GEARS 4 Sheets-Sheet l Nov. 28, 1961 0 F. PERRUCA 3,010,330

FRICTION TYPE CHANGE SPEED GEARs Filed Jan. 28, 1959 4 Sheets-Sheet 2 Nov. 28, 1961 F. PERRUCA FRICTION TYPE CHANGE SPEED GEARs 4 Sheets-Sheet 3 Filed Jan. 28, 1959 Nov. 28, 1961 F. PERRUCA FRICTIQN TYPE CHANGE SPEED GEARs 4 Sheets-Sheet 4 Filed Jan. 28, 1959 United States Patent Olce 3,010,330 Patented Nov.` 28, 1961 pany Filed Jan. 28, 1959, Ser. No. 789,539 Claims priority, application France Feb. 19, 1958 Claims. (Cl. 74-200) This invention relates to friction type change speed gears.

An essential condition for correct functioning of such gears is that frictional `contact between the frictional contact members should be substantially perfect. A very slight amount of slip between these members tends to damage contact surfaces thereof.

Although frictional contact members can be composedk of materials which have high coefcients of friction, the wear on these members is in this case very rapid.

An advantageously adopted solution consists in forming the ictional contact members of metal, and more particularly of steel which has been suitably hardened by appropriate alloying. These members are very strong, the eflciency of the frictional contact depending solely on the pressure or pressures which are applied to the friction members. Apparatus have already been proposed which automatically effect, between the friction members, a pressure which is proportional to the resistant torque of the output shaft.

The use of very high pressure is not without disadvantages. Such pressures not only contribute to the provision of very good frictional Contact, but cause considerable unbalanced forces to occur, which forces tend to buckle the friction wheels and to strain the spindles or shafts carrying the wheels. This complicates the construction of change-speed gears and limits the power which such gears are capable of transmitting.

It is an object of the invention to provide a friction type change speed -gear having two transmission shafts, in which gear the pressures obtaining when the gear is in operation are evenly balanced against one another.

It is a further object of the invention to provide such a gear in which owing to the aforementioned balancing of said pressures, the resultant pressures obtaining when the gear is operating are directed axially of a single shaft, whereby the casing of the gear can be of substantially light construction.

It is a further object of the invention to provide such a gear in which the driving forces employed can be of substantially ldouble the value of those that are ernployed in conventional friction type change speed gears.

It is a further object of the invention to provide such a gear, in which slip between the frictional contactY members is substantially eliminated.

It is a further object of the invention to provide such a gear which is of substantially simple and economicalconstruction.

According to the present invention there is providedA a friction type change speed gear, comprising a driving shaft, a secondary shaft, a plurality of transmission shafts oi-set from alignment with said driving Shaft and con` resides in the novel features of construction and combinations and arrangements of parts as more fully hereinafter set forth.

In the drawings:

FIGURE 1 is a side elevational view, partly in section of a friction type change speed gear according to the invention;

FIGURE 2 is a plan view, partly in section of the change speed gear shown in FIGURE 1;

FIGURE 3 is an axial View, partly in section of a Vpressure device for a friction type change speed gear,

for use with the change speed gear shown in FIGURES 1 and 2;

FIGURE 4 is a diagrammatic sectional side elevational View of the change speed gear shown in FIGURES 1 and 2;

FIGURES 5 and 6, each shows a front elevation View and a side elevational view in section of a detail of the device shown in FIGURE 3;

FIGURES 7 and 8, each is an elevational view, partly in section of part of a friction-type change speed gear according to the invention;

FIGURE 9 is a perspective View of a detail of the parts shown in FIGURES 7 and 8. t

Reference will now be made to FIGURES `1 and 2 of the accompanying drawings. A frame 1 which may in the interests of economy be of substantially small wall thickness, since as will be hereinafter described, the pressures obtaining when the change speed gear is in operation are arranged to be taken up by an intermediate shaft 11, is shown in axial section. A primary shaft 2 to which a driving torque is arranged to be applied, is rotatably mounted in ball bearings carried by a bearing element 12 arranged in an inner wall -11 of the frame 1, and by a bearing element 31 carried by a closure plate 3 attached to vthe yframe 1 so as to close the open end thereof.

A gear wheel 4 is keyed to the primary shaft 2 and is arranged to mesh with two substantially identical gear wheels 5 and 6, which gear wheels are keyed respectively to shafts 7 and 8. The shafts 7 and 8 are rotatable in antifriction bearings arranged in bearing ele-- ments 13 in the wall 11, and bearing elements -14 in the frame 1. Identical driving friction wheels 9 and 10 are mounted respectively on the shafts 7 and 8. The shaftV 11 is mounted at one end thereof so as to be rotatable in the bearing element 12 in an antifriction bearing, the other end of the shaft 11 being connected to a pressure device rotatably connecting the shaft 11 with an output shaft '15, carried by a support 15 xed to the frame 1. The axial position of the shaft '11 is iixed by the antifn'ction bearing of the bearing element 12.

VAn abutment wheel .12 is keyed to the shaft 11 for rotation therewith and frictionally engages friction rollers 17. `A driven friction wheel 13 is fixed relative to the shaft' 11 for rotation therewith. The driven wheel 13 is keyed to a conicalrelement 141 fixedly mountedV on a sleeve 14 on the shaft 11. The sleeve 14 is normally rotatable with the output shaft 15 via the said pressure device, which device is arranged to provide a pressure which is automatically proportional to the torque to bev balance the pressures exerted by the driving wheels 9 and 10 in the direction of the abutment wheel\12. The rollers 16 and 17 which are identical with one another .have conical bearing surfaces 161 and 171 respectively.

The bearing surfaces 161 are arranged to bear against The friction rollers 17 kinematically connect the abutment wheel 12 to the `driving wheels 9 and 10, and

d the driven wheel 113 and the wheels 9 and 10, and the bearingV surfaces 17l are arranged to bear against the wheels 9 and 10 and the wheel 12 at an angle as shown in the drawings,. so as to eliminate the effects of relative diiferences in speed over theV width of the bearing surfaces 161, 171.

Each roller 16 and -17 is mounted so as to be freely rotatable in anti-friction bearings on a; pin 18 (FIG. 8). Each pin 18 has attened ends 181 (FIGS. 7, 8 and 9), which ends are fixed for example by means of screws to lugs 191 on a supporting sleeve 19. The lugs 191`are recessed Vat 192 to permit maximum displacement radially of the friction wheels with which the rollers are in contact without the lugs bearingragainst either of the shafts 7, 8 or 11.-

The sleeves 19 (see FIGV7) are slidably mounted on, so as to be guided by, regulating shafts 20, 21, which shafts are rotatably mounted in anti-friction bearings and. ball typethrust bearings, in bearing'elements 22 and 23 (FIG. 1) carried respectively in the bottom andi top portions of the frame 1;` The shafts 20 and 21 are provided 4towards the ends thereof with threaded portions 201 and 211. The threadsof'the threaded portions of each shaft 20, 21 are of the same pitch, but are directed in opposite senses to one another. The shafts 20 and 21 are so arranged that the threads of yadjacent portions 2131 and 211 are oppositely directed. Threaded nuts24 are disposed in recesses '193 in the sleeves 19 and are' arranged to cooperate with the threaded portions 201 and 211 so that the sleevesV 19 can be displaced on the shafts 20, 21, whereby displacing'the rollers 16, 17V

radially of the wheels 9, 1t); 12 `and 13.

The nuts are held against rotation by means of keys 25 fitted in radial slots formed in the ends of the sleeves 19, and in the nuts 24. A square nut or driving head lrollers 16 and 17 are displaced over an equal distance and in the same direction radially of the shaft l11. The positions of the rollers 16, 17 should be initially regulated so that the rollers are arranged at equal distances from the axis of the shaft 11. Such regulation should beV eifected before mounting the keys 25 andthe pinions 2-7 and 28. The considerable pressure necessary to ensure the required friction between the rollers and the wheels 9, 10; and 12, 13, can be obtained by employing known arrangements.

Such a device is shown in FIGURE 3. Resilient means comprising a helical spring 29r of substantially square cross section is arranged to apply a continuous pressure against the driven wheel 13.` One end of the spring bears against a shoulder in the bore of the sleeve 14, the other end of the spring bearing against a ringV 30 which is frxedly attached to the shaft 11. lIn order to obtain a working pressure between the rollers 16, 17 and the wheels 9, 10; and 12, 13, which are in frictional contact with said rollers, which pressure is directly proportional to variations obtaining during operation of the gear in the'resistance torque of the output shaft 15, -a

pressurernember 31 (FIG. 6) xed tothe sleeve'14 is provided, Vtherebeing a second pressure member (FIG.V

) which is keyed in a bore of the output shaft Y15 and is rotatable with said shaft; The members 31 and 32 are provided with inclined surfaces 311 and 322, which surfaces are adapted to engage one another so that the shaft 11 can drive the shaft 15. The saidfinclined surfaces of thepressure members comprise ramps 311, 322V (FIGS. 5 and 6) which are in plan view arc shapedY and i and the resistance torque, the members 31 `and 32' are displaced angularly with respect to one ,anotherV during operation of the change speed gear; This angular displacement is converted into a substantial axial pressure due to cooperation between'inclination `of the surfaces of the ramps of one member with those of the other member. The continuous pressure of the spring 29 is additive to the said axial pressure.V The reqiured working pressure for urging the rollers against the wheels 9, `1l); and 12, 13 is thus'obtained at all working speeds. rI'he speeds obtained at the output shaft can be ascertained by means of an indicator (not shown) having indicating means displaceable in accordance with the displacement of the rollers V16 and 17 radially of the axis of the Y shaft 11.

plates 9 and 10 will now be considered.

In order to take up play which may occur between the pressure members, a helical spring 33 (FIG. 3) is arranged so as to have high circular tension in the output shaft 15. The other endV of the spring is fixedly attached to a nut 314 screwed to the threaded end 34 of the shaft 1.1, so that the nut is rotatable on the thread. The nut bears against the pressure member 32 via an antifriction bearing 35, and thus applies pressure to the whole system of pressure'members, rollers and wheels. If even a small amount of play occurs, the nut 34 is end of the shaft 11 s o as to take upl the play.v

Y Reference will now be madev to FIGURE 4 of thel accompanying drawings. The manner in which the driving torque ofthe primary shaft' 2 is applied to the the main forces obtaining when the Vchange speed gear is in operation are indicated by '.arrows. It will be'l apparent from the ligure that the forces and pressures obtaining at the wheels and rollers act finally substantially only on the shaft 11, since the wheels 12 and 13 are fxedly mounted on the shaft'11, the shaft being driven by traction. Theabove described change speed gear may be modified in various ways within the scope of the invention.

What I claim as my invention is:

1. A gear device comprising a rotatable driving shaft, transmission shafts parallel to and radially spaced from said driving shaft, gear wheels coupling the driving shaft to the transmission shafts for driving the latter, friction wheels on and driven by the-transmission shafts, an intermediate shaft coaxial With said driving shaft, an abut- Yment wheel xed on and rotatable with said intermediatel shaft, a driven wheel axially displaceable on but rotatable with said intermediate shaft, saidfabutment and driven wheels being spaced and accommodating therebetween said friction wheels in spaced relation thereto, friction rollers between said friction wheels and said abutment and driven wheels and defining axes oblique to said wheels, said rollers having frustoconical surfaces engaging said wheels, an output shaft coaxial with said intermediate shaft, pressure members on said yintermediate and output shafts and in axially abutting relation and play take-up means engaging the pressure members to take-up play therebetween and provide a yieldable driving relationship between said intermediate and output shafts, said pressure members including and being provided with ramps and accommodating ygrooves and being axially separable upon relative angular displacement, said driven wheel being coupled to'one of said pressure members for `axial displacement therewith Vand'for driving the same, an axial displacement of said driven wheel varying lIn FIGURE 4 3,010,330 6 the transmission of torque from the friction Wheels to said positionally adjusting said friction rollers both separately driven WheeL and simultaneously.

2. A device as claimed in claim 1 comprising means supporting the friction rollers for simultaneous adjust- References Cited m the me of this patent ment in like radial directions relative to the intermediate 5 UNITED STATES PATENTS Shaft, 1,544,697 Stoeckicht July 7, 192.5 3. A device as claimed in claim 1 wherein the other of 218351134 Perruca May 20 1958 the pressure members is keyed With said output shaft. FOREIGN PATENTS 4. A device as claimed in claim 1 wherein said ramps 10 530,550 France. Aug 23, 1927 are threads of square section and of less than one pitch. 255,798 Switzerland July 15, 1948 5. A device as claimed in claim 1 comprising means for 650,166 Great Britain Feb. 14, 1951 

